Microwave-frequency (SHF) circuits of a variety of applications embodied in a semiconductor chip mounted on a base plate and usually contained within a housing are provided with relatively large pins for making connection to a printed-circuit board (PCB) or other substrate. The parasitic capacitance between one or more pins and the baseplate may, however, be unacceptably large, and may seriously degrade circuit performance.
Previous attempts to ameliorate this problem have involved tuning-out the parasitic capacitance with a microstrip line stub to ground, or by an on-chip inductor. Both of these techniques have their disadvantages as will be described later.
It is common practice in the art to ground the chip's ground connection to the base plate and to a ground pin using any suitable arrangement of bonding wires, and to connect the base plate to the ground of the PCB or other substrate.